Splitboarding (FIG. 1) is a well known winter sport and is growing internationally. Derived from snowboarding, the splitboarder may disassemble the board into two pieces and either carry the two ski halves or ski uphill (using climbing skins) to a backcountry destination; then reassemble the board halves and ride downhill as shown. To achieve this mixed function, two boot binding interfaces are provided: a “ski tour interface” is used for ski touring, and a “board ride interface” is used when riding a “solid board” configuration (sometimes termed “ride mode”, or descent mode”) in which the two ski members are conjoined as a single gliding board member (FIGS. 2-3). Riders are also increasingly using splitboards in-bounds and on lifts because of their flexibility in alternating between “tour mode” and “ride mode”.
Splitboards were first made by Ueli Bettenman, as described in European Pat. Doc. Nos. CH681509, CH684825, German Gebrauchsmuster DE9108618 and EP0362782B1, first under the tradename Snowhow, and later in conjunction with Nitro (Seattle, Wash.). Advantageously, the rider's legs are rigidly anchored on the splitboard in ride mode, reducing the risk of knee injury associated with downhill skiing, but preserving the advantages of skis for cross-country and uphill skiing whenever needed by enabling the board to be “spilt” apart into skis.
Another early entrant commercially was Voilé (Salt Lake City, Utah). The popular “Split Decision” introduced a binding system essentially as described in U.S. Pat. No. 5,984,324 to Wariakois. The patent describes a “slider track” with insertable toe pivot pin for each foot, the slider track joining pairs of “pucks” mounted crosswise on each ski member and also serving as a pivot axle for free heel touring. This innovation resulted in substantial growth of interest in splitboarding in the United States and has had a worldwide impact on the sport. Ride mode interfaces of this type have been tested for over twenty years and have demonstrated a high level of consumer acceptance. However, there has been little innovation in the “pucks” during the almost twenty years of their use.
Ritter, in U.S. Pat. Nos. 7,823,905, 8,226,109, 9,022,412 and 9,126,099, described a stiffer, lower and lighter boot binding and interface system for using in ski and ride modes. The products are being commercialized by Spark R&D of Bozeman Mont.
Threaded inserts 91 are typically embedded in the board and are used conventionally to secure the pairs of sliderblocks to the board surface. However, conventional sliderblocks require a particular combination of slotted disks (FIGS. 3-4) that limits the operable stance adjustment by the rider to stepwise increments in length on the long axis of the board. Also, at least one such sliderblock is not readily adjustable in the crosswise dimension on the board, meaning that some riders may not achieve optimum foot positioning.
Conventionally, a reinforced nylon sliderblock having significant elasticity is used. The compliance of the material can reduce mechanical coupling between the board and the rider, limiting ride control. Efforts to reduce this elasticity have included substituting an all-metal binding interface (such as described by Maravetz in U.S. Pat. No. 6,523,851, Riepler in U.S. Pat. No. 8,033,564, and Kloster in U.S. Pat. No. 8,469,372), broadening the binding baseplate (Ritter in U.S. Pat. Nos. 9,022,412 and 9,126,099), and forming a modified sliderblock out of a metal or a stiffer composite (Ritter, patent pending).
While significantly stiffer, a metal puck was found to have an immediate disadvantage. Over time, the binding interface has been found to scuff and bite into the board surface and the inside rails of the binding, leading to looseness and reduced valuation of the used equipment. The metal puck also has limited elasticity, and hence cannot be as readily used in recreational maneuvers such as a foot roll, where a more elastic puck would allow the rider to lean into the board so as to load a spring force onto the block and then recover from the lean by letting the puck spring back, returning the force to the rider. For reference, optimal torsional stiffness of the entire binding system (including a boot) is in the range of 70 to 130 inch-lb/degree (Ritter, U.S. Pat. Nos. 7,823,905 and 9,022,412). Stiffness of the conventional puck (with box girder) is a substantial part of the total stiffness, and is about 150 to 300 inch-lb/degree when treated as part of a lever arm. Most conventional boots and boot binding systems provide much less stiffness. Thus, the elasticity of conventional blocks in the splitboard ride interface has been either too elastic or too stiff, and improvement is not readily accomplished except by trial and error.
Another problematic aspect relates to board construction. The boot binding interface must be affixed to the board using fasteners and embedded nuts termed “inserts” 91, but the installation of nuts in the board is difficult to standardize. Typically a row of inserts are placed in splitboards; a four-hole pattern is used for snowboards. Channels for moveable fasteners, termed “T-nuts”, may also be cut for more flexibility. However, manufacturing tolerances associated with shaping and lamination processes can result in boards having asymmetrical arrays of inserts that only approximate an ideal position equidistant from the centerline of the board. These imperfections can shift the boot binding interface off the centerline and can affect the rider's balance, or lead to heel or toe drag (FIG. 1, 2a). When off center, heel turns will be less responsive than toe turns (or vice versa) depending on whether the binding is biased toewise or heelwise relative to the centerline of the board. Unfortunately, conventional mounting systems limit crosswise adjustment of the toe and heel, “crosswise” indicating an adjustment of the binding position relative to the lateral edges of the board. Thus it can be said that current systems are designed to facilitate adjustment with two degrees of freedom (one rotational, the other on the long axis of the board), but it has become apparent that a third degree of freedom (side-to-side) is also needed. There is currently no system for centering the boot binding interface (and stance) crosswise on the board while flexibly adjusting the separation distance between the sliderblocks. The difficulty increases as the sliderblocks are angled (relative to the long axis of the board), some riders preferring 20 or even 25 degrees of puck assembly angulation relative to the centerline axis of the board. Thus there has been a long-standing need for a boot binding interface system that overcomes these difficulties and is readily adjustable, with three degrees of freedom—including a toe-to-heel centering adjustment relative to the lateral edges of the board—according to a rider's preferred stance on the board. Most preferably, any innovation that meets this need would be adaptable to most of the boot binding interfaces and fastening systems currently available.